Synchronisation of gilts by an altrenogest oral solution in a Korean herd

Altrenogest is used worldwide to synchronise sexual cycle of replacement gilts before their introduction in the reproductive herd. Objective of this study was to test efficacy of a 0.4% altrenogest oral solution (Virbagest®, Virbac) for gilts synchronization in a large Korean farm.

Selected herd comprises 2,500 sows managed according to 1-week batch farrowing. Twenty to 30 replacement gilts are introduced weekly in each batch. Target is to service 240 days old gilts weighing around 140 kg. Two hundred seventy cycled gilts were included in summer during 10 successive weeks per batch of 25 to 30 each. The altrenogest oral solution was given orally for 18 days at the dose of 18 mg/d. Oestrus was detected after stop of treatment by boar stimulation twice daily. Gilts showing standing reaction were serviced twice 24 h apart by artificial insemination. Pregnancy was diagnosed twice by ultrasonography (27 and 34 days after service). Regular and irregular returns were checked till 7 weeks after service. The 95% confidence intervals (CI) were calculated for rate of gilts showing oestrus and pregnancy rate.

Out of the 270 treated gilts, 262 showed oestrus and were serviced (97.0%, CI = 95.0% -­ 99.0%). Grouping of oestrus was obtained within 3 days for 99.2% of serviced gilts (6 to 8 days after stop of treatment). Pregnancy rate among serviced gilts was equal to 95.0% (CI = 92.4% -­ 97.6%).

Reproductive performances of the treated gilts will be followed till weaning of first litter.

This study confirmed the accurate grouping of gilts oestrus following treatment with the tested altrenogest oral solution. Such synchronisation allows an anticipated introduction of replacement gilts whatever the type of batch management, with well known advantages (optimisation of the number of required gilts and selection of them at the right time, stability of replacement rate over time, heat detection focused on a few days).

Disclosure of Interest: None Declared.